Can thicker oil cause more wear?

ZeeOSix

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Yep, I've posted that article before too. Other studies show basically similar information. That's why I use 5W-30 to keep the HTHS viscosity above 3.0 cP.
 
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I have issues with that article. Where's the methodology? What's the reference engine? The first graph for fuel savings is comparing to a 15W-40. There's few gas oils in that grade so are they referencing a diesel engine here? Which one? If a gas engine, which one? How was this tested? What were the conditions? There's no scientific method provided so the data is useless.

I could see a turbo diesel, meant for a 40 grade oil with big crank journals, wide clearances, high side loading, and high cylinder pressure at very low rpm, not liking an HTHS of 2.6 cP or 2.3 cP. My NA 3.7L V6 gas engine, that cruises easy down the highway, likely couldn't care less.

I also pulled up the author of that article on Linked In where it shows he's in sales at Q8. Not a formulator, not a tribologist, but a marketing desk jockey. It's also posted on his employing brand's page with no reference to any lab or persons who conducted the study, no reference to any technical article(s) to support the information, and is written like classic marketing literature.

Given all of that, I'm chalking it up as a marketing word salad with no substantial content.
 

ZeeOSix

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This is from a controlled study ... I'd have to go search for the full study, but this is one of the data graphs. Seems to be very similar to the graph given earlier. IIRC, the SWRI (Southwest Research Institute) also did some engine wear study with irradiated engine parts to determine wear rates vs oil viscosity and HTHS viscosity.

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Yes, another thick vs thin thread, but this one's a little different. Let's take my car for example (just to make it simple), it specifies a 5w-20, 5w-30 or 10w-30. Let say I decide to run a 5w-40 or even just for discussions sake, a 15w-50 oil for the life of the engine. No VVT codes or other strange things happen, and the vehicle is always started in warm weather (we'll say no colder than 72°F). Is there any mechanical or scientific reason that running a thicker oil could cause increased wear?
The only real concern would be more start up wear. Thicker oil takes longer to pump up to the valvetrain of the engine.
 

ZeeOSix

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^^^ The positive displacement (PD) oil pump ... the most misunderstood thing on car chat boards. :D
 
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How much 0-20 wateroil will cling to parts between startups against 20-50...I bet that wateroil will leave parts dryer than a popcorn fart..
 
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Please explain how 2 fluids of different viscosities Move at different rates oin confined channels through a PD pump.
Once the oil gets to the valve train though, I believe the lubrication is no longer direct for many components, cam lobes and lifter interface for example. I recently adjusted the OH valves on my generator as they were a little too loose and then ran it with the valve cover off, and I was surprised how little oil was being supplied and splashing around up there. If your engine is pumping honey for a minute or two I think some valve train parts wouldn't be getting new oil for a while.
 

ZeeOSix

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well...when the oil is cold and molasses like most dumps out the relief valve...just sturrin...
True, but it would have to be mighty cold with something like a 10W or higher and some engine revs way above idle to make the PD go into relief. Best practice is to never rev an engine much over 2000 RPM on a super cold start-up day until the oil warms up a lot. Once oil is warmed up you would be hard pressed to get the pump to hit relief unless you were real near to redline, regardless of the oil being used.
 

ZeeOSix

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Once the oil gets to the valve train though, I believe the lubrication is no longer direct for many components, cam lobes and lifter interface for example. I recently adjusted the OH valves on my generator as they were a little too loose and then ran it with the valve cover off, and I was surprised how little oil was being supplied and splashing around up there. If your engine is pumping honey for a minute or two I think some valve train parts wouldn't be getting new oil for a while.
If a valve train was "starved" of oil and not lubricated adequately in a cold start situation while using the W rating the manufacture called out, then it would basically stem from a lubrication oiling design flaw. An engine lubrication system design needs to take into account the coldest start-up conditions (using specified oil viscosity) and ensure that adequate flow of cold oil lubricates everything.
 
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When my uncle and Dad ran circle track years ago the motors had solid lifters and required feeler gauges. I would set them while running without valve covers and oil got all over everything....crap load of oil out the pushrods.
 
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True, but it would have to be mighty cold with something like a 10W or higher and some engine revs way above idle to make the PD go into relief. Best practice is to never rev an engine much over 2000 RPM on a super cold start-up day until the oil warms up a lot. Once oil is warmed up you would be hard pressed to get the pump to hit relief unless you were real near to redline, regardless of the oil being used.
Around 1981 or so my pickup was low on oil and was in a hurry not to be late to class. No oil was to be had but there was some 90-130 gear oil so...
Weather got cold suddenly couple of weeks later and I ran out to warm up the truck. It started okey but when I came out later to get to class it was not running. Upon inspection one could easily spin the distributer by hand. New cam and distributer...
 
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Around 1981 or so my pickup was low on oil and was in a hurry not to be late to class. No oil was to be had but there was some 90-130 gear oil so...
Weather got cold suddenly and I ran out to warm up the truck. It started okey but when I came out later to get to class it was not running. Upon inspection one could easily spin the distributer with my hand. New cam and distributer...
 
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This is from a controlled study ... I'd have to go search for the full study, but this is one of the data graphs. Seems to be very similar to the graph given earlier. IIRC, the SWRI (Southwest Research Institute) also did some engine wear study with irradiated engine parts to determine wear rates vs oil viscosity and HTHS viscosity.
That chart is difficult for me to take seriously, considering that the test conditions are not revealed, and that whoever drew the nice smooth curves apparently ignored that the data points, at most test speeds, strangely seem to show wear was lower at 2.6 cP than at higher, as well as lower HTHS oils. How do we know the testing wasn't done in an engine designed for xW-40 oil, or at an unrealistically high sump temperature?
 

ZeeOSix

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That chart is difficult for me to take seriously, considering that the test conditions are not revealed, and that whoever drew the nice smooth curves apparently ignored that the data points, at most test speeds, strangely seem to show wear was lower at 2.6 cP than at higher, as well as lower HTHS oils. How do we know the testing wasn't done in an engine designed for xW-40 oil, or at an unrealistically high sump temperature?
It's called curve fitting the data. Overall, that chart is saying wear increased with higher RPM and increased with lower HTHS. Keep in mind that higher engine revs causes motor oil to shear more and that can cause the viscosity to decrease due to the shearing effect. So it makes perfect sense that more wear would occur in the ring pack with higher engine revs.
 
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